Feature #15722
Updated by sawa (Tsuyoshi Sawada) almost 5 years ago
I often want to use `===` to match a single object on the right side against multiple objects on the left, as is used in `case`-constructions, just to return a truth value, and end up writing like this:
```ruby
bar # => "bar"
flag1 = case bar; when "foo", "bar", "baz"; true; end # => true
flag2 = case bar; when Symbol, String; true; end # => true
```
I propose `Kernel#case?` that should work like this:
```ruby
bar # => "bar"
bar.case?("foo", "bar", "baz") # => true
bar.case?("qux") # => false
bar.case?(Symbol, String) # => true
bar.case?(Array) # => false
bar.case? # => false
```
It is similar to Rails' `in?`, but it differs from it in that it uses `===` for comparison, not `==`.
Or, alternatively, allowing `Kernel#instance_of?` and `Kernel#kind_of?` to allow multiple arguments may be a compromise.